#define  _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int main()
{
	int a;
	int b;
	int c;
	int d;
	int e;
	float sum;
	scanf("%d %d %d %d %d", &a, &b, &c, &d, &e);
	sum = (a + b + c + d + e) / 5.0;
	printf("%.1f", sum);

	return 0;
}